Computing devices may store data in more than one place. When the same or related information is stored in two places, it is possible for the data to change in one location (store) and not in another. Synchronization methods have been developed to propagate the changes between the different stores, so that the information in the different stores correlate to each other.
In one method, during synchronization, changes to the data in the different stores are collected, compared, and reconciled. The synchronization process itself involves making changes (“sync changes”) to the data stores in order to “update” or propagate the changes made in other stores. All of the required changes to synchronize the stores may not be completed during each synchronization attempt. For example, a connection between stores may be broken during the process causing the synchronization attempt to be incomplete. One store, however, may indicate that synchronization has completed successfully when in fact the synchronization was unsuccessful.
In another method, changes are sent incrementally between the stores using notifications as the changes occur. Some implementations utilize both of these methods together.